Aug. 6, 2012 -- Two brain regions go on high alert when hoarders must decide whether to keep something they own or throw it away.

In a new study in Archives of General Psychiatry, brain images of those regions show that hoarders respond quite differently when making such decisions than people with
obsessive compulsive disorder and people without any
mental disorder.

"That brain network goes into hyperdrive, starts freaking out," says researcher David Tolin, PhD, a psychologist at the Institute of Living in Hartford, Conn. "The task seems to overload the network."

When it comes to their own possessions, says Tolin, the decision-making process for hoarders becomes very difficult, even painful, so they avoid it. And so, stuff keeps piling up.

"It's very common, and it can be very sad," he says.

Decisions, Decisions

To help see what happens in hoarders' brains at the moment of decision-making, Tolin and his colleagues recruited 107 adults for their experiment. Forty-three of them were hoarders. Thirty-one had been diagnosed with obsessive compulsive disorder (OCD). The remaining 33 were healthy.

Each was told to bring in a load of paper items such as junk mail from around their houses. While an fMRI machine took real-time images of their brains, the recruits were asked to decide whether to keep or throw away each item.

They were also asked to decide the fate of stuff that did not belong to them. Tolin brought in a bag of his own junk mail, which he had collected for the previous six months. The participants were shown their own stuff and Tolin's in random order during sessions that lasted about an hour.

The brains of the hoarders showed little response when confronted with Tolin's credit card offers, Netflix coupons, and other junk. Asked about their own, similar belongings, the hoarders' brains -- specifically the anterior cingulate cortex and the insula -- both showed abnormal activity.

"The only real difference between the stuff was the name on the address label," says Tolin. "And the affected brain regions really flip flopped on the basis of ownership."

Tolin says those regions are known to play a big role in assigning importance and relevance to objects. For someone with arachnophobia, for example, seeing a spider would activate those areas in a big way. Hoarders have the same type of brain reaction, the study shows. Their brains assign undue importance and relevance to things that most people would consider junk.

Hoarding Distinct From OCD

The other participants in the study showed no such reaction to the decision-making process. Although that may not be surprising for the healthy group, it is a telling detail regarding OCD. Tolin says that until recently, hoarding has been considered a component or sub-type of OCD. The fact that different brain regions are at play in the two groups is evidence that the two disorders are distinct.

Psychiatrist Sanjaya Saxena, MD, who has also published imaging studies of hoarders' brains, says that Tolin's work is important.

"This is the largest brain-imaging study of hoarders, and it's rare to get papers like this where you have such a large group," says Saxena, who directs the OCD Clinic at the University of California, San Diego. "There have only been a handful of such studies, but the results are beginning to converge."

Saxena estimates that 3% to 5% of the population has hoarding disorder. "Hoarding is much more common than OCD, and it is a very understudied disorder," says Saxena, who reviewed the study for WebMD.

"The takeaway from this study is that more and more data show that hoarding is a separate disorder and needs to be treated as such," says Travis Osborne, PhD, a clinical psychologist at Evidence Based Treatment Centers in Seattle.

Osborne, who was not involved in the research, sees many hoarders in his practice. Treating them, he says, is a real challenge.

"People who hoard get stuck because of problems with decision making," he says. "To clean out their homes means making thousands or tens of thousands of decisions about what to throw away. They have to decide about every single piece of paper. This study of decision-making lends concrete support to what we see clinically."